In the present state-of-the-art of packaging microcircuitry, printed circuits, and other sensitive electronic equipment, it is known that such circuitry needs to be protected against electrostatic discharges such as might occur when a person touches the equipment. Usual prior art precautions to prevent damage consist of grounding the frame or chassis particularly in the area of the access compartment of the housing so that any electrostatic build up in a person is transferred to ground before he can touch the sensitive equipment.
In some cases the grounding of the chassis or frame, either completely or at the area of the access port, is not sufficient to prevent certain kinds of problems. For example, when electronic circuitry includes parts that can respond to radio frequency signals such as the flip-flops and other components of microprocessors, then, when the person touches the outside of a grounded chassis, a spark may result which causes RF interference. This RF interference is believed to be projected from the inside surface of the grounded chassis and thus capable of effecting the electronic components. For example, the RF interference could then set flip-flops in a wrong state and thus cause "lock-up" of the microprocessor.
Accordingly, it is important not only to ground the electrostatic charge in a person, but also to prevent the possible sparks from causing problems.